Manufacture of elastic yarns



Aug. 8, 1967 P. N. MILNE MANUFACTURE OF ELASTIC YARNS Filed April 20,1965 2 Sheets-Sheet 1 INVENTOR PERCIVAL NORMAN MILNE ATTORNEY Aug.8,1967 P. N. MILNE MANUFACTURE OF ELASTIC YARNS 2 Sheets-Sheet Filed April20, 1965 FIGS.

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INVENTQR PERCIVAL NORMAN MILNE ATTOR N E Y United States Patent M3,334,478 MANUFACTURE OF ELASTIC YARNS Percival Norman Milne, Oadby,Leicestershire, England, assignor to Chemstrand Limited, London, EnglandFiled Apr. 20, 1965, Ser. No. 449,439 Claims priority, application GreatBritain, Apr. 21, 1964, 16,511/ 64 6 Claims. (CI. 57-12) This inventionrelates to the spinning of textile yarns and is concerned moreparticularly with the spinning of high-bulk composite elastic yarnsconsisting of an elastic filament constituting an elastic core aboutwhich is spun a sheath of drafted rovings of staple fibres.

A known method of spinning elastic high-bulk textile yarn consists inpassing a straight elastic filament through a tensioning device,combining the filament with a nonelastic roving and twisting thefilament and the roving on a spinning frame. Whilst undergoing suchtreatment, the elastic filament is maintained in a stretched condition.When the elastic filament is allowed to contract, the sheath fibresbulge outwardly to provide a high-bulk yarn. A disadvantage of this andother known methods of producing high'bulk elastic yarns is that theylack infinite control of the elastic filament so that non-uniform oflF-winding tensions of the elastic filament and drafting of the non-elasticroving occurs with the result that the composite yarn has impartedthereto irregularities in the elongation and other physical propertiesof the yarn which is undesirable.

It is an object of the invention to provide a method of spinning anelastic yarn in which the aforesaid disadvantages are obviated.

According to the present invention there is provided a method ofspinning an elastic high-bulk yarn comprising the steps of providing anelastic filament wound under tension onto a package, causing saidpackage to rotate at a predetermined speed, unwinding said filament fromsaid package at a predetermined linear speed, feeding said filament ontoa positively driven pulley to cause said filament to travel in anundulating path and to restrain it against slippage, advancing saidfilament under uniform tension through a drafting zone, drafting one ormore rovings of inelastic filaments, gathering said elastic filament andsaid drafted rovings in a final drafting zone and thereafter twistingsaid rovings about said elastic filament to form a sheath thereto.

The invention is illustrated by way of example in the accompanyingdrawings, in which:

FIGURE 1 is a diagrammatic representation of an apparatus for carryingout the invention.

FIGURE 2 is a part-sectional side view of a pu ley employed in theapparatus diagrammatically illustrated in FIGURE 1.

FIGURE 3 is a front elevation of one of the parts from which the pulleyillustrated in FIGURE 2 is constructed.

FIGURE 4 is a sectional view taken on the line A-A of FIGURE 3, and

FIGURE 5 is a front elevation looking in the direction of the arrow B inFIGURE 2.

Referring to the drawings, a cylindrical package 1 has wound thereon acontinuous elastic filament 2. The package 1 is disposed between a pairof drive rolls 3, suitable brackets (not shown) being provided to holdthe package 1 between the drive rolls 3. The drive rolls 3 are adaptedto be positively driven through suitable gearing and serve to unwind theelastic filament 2 from the package 1 at a predetermined linear speed.The elastic filament 2 is fed to a V-pulley 4 mounted on a shaft 5, therotational speed of which can be varied so as to afford a predeterminedamount of elongation to the elastic fila- 3,334,478 Patented Aug. 8,1967.

ment 2 as it is fed to the nip of a pair of final draft rolls 6 and 7.The elastic filament 2 is fed from the pulley 4 between the nip of apair of rolls 8 and 9. Packages 10 and 11 supply rovings of inelasticstaple fibres 12 and 13 to a conventional drafting system comprisingpairs of rolls 14 and 15, as illustrated, or a series of drafting apronsor a combination of drafting rolls and aprons. The drafted inelasticstaple fibre rovings 12 and 13 together with the elastic filament 2 arepassed between the final draft rolls 6 and 7 and thence through a guide16 to a conventional twist means (not shown) whereby the rovings 12 and13 are wound around the elastic filament 2 to form a sheath. Thecomposite yarn is then wound onto a bobbin 17.

Rolls 8 and 9 are driven at a speed which is correlated with the speedof the rolls 6 and 7 to provide the desired amount of elongation of thefilament 2 in the span between the rolls 8, 9 and 6, 7. The rotationalspeed of the pulley 4 is correlated with the rotational speed of therolls 8 and 9 to provide the desired amount of elongation of the elasticfilament 2 in the span between the pulley 4 and the rolls 8 and 9. Thepulley 4 in effect provides a pretensioning of the elastic filament 2 toinsure that this filament passes between the rolls 8 and 9 at apredetermined constant tension. Without the pulley 4, the elasticfilament 2 would pass between the rolls 8 and 9 under a tension which isin part a function of the tension with which the elastic filament iswound onto the bobbin 1. Since this tension is not constant, it canreadily be seen that, without the pulley 4, the tension in the yarnentering the rolls 8 and 9 would vary to some extent. These variationswould be carried to some extent beyond the rolls 8 and 9 and would thusresult in a somewhat varying tension in the span between the rolls 8, 9and 6, 7, with the result that the end product would not be uniform inconstruction. The pulley 4 insures that. the elastic yarn entering therolls 8 and 9 is held at a substantially constant elongation orpretension so that the total elongation applied to the filament in thefinal draft zone (between rolls 8, 9 and 6, 7) is constant.

Referring to FIGURES 2 to 5 of the drawings, the pulley 4 comprises apair of dished plates 18 each of which is formed with a plurality ofequidistantly spaced radial tongues 19 which are inclined outwardly. Theplates 18 each have a central aperture 20 for the reception of a boss 21whereby the pulley is mounted on the shaft 5. The plates 18 areassembled so that the tongues on one plate interengage the gaps betweenthe tongues on the other plate, the plates being secured in theassembled position through the medium of a shoulder 22 On the boss 21,the outer end 23 of which is punched over so that the plates are held infirm engagement with each other. After the plates 18 have beenassembled, a hoop 24 is press-fitted onto the outer edge of each plateso as to provide a smooth finish thereto. By constructing the pulley inthe manner described, the periphery of the base of the pulley groovewill provide an undulating, e.g. corrugated, surface. When the elasticfilament is in engagement with the pulley groove, it will follow anundulating path whereby a restraining action will be exerted on thefilament and slippage thereof will be prevented, thus ensuring that thefilament is fed uniformly to the final drafting zone and that thecomposite yarn will be free from irregularities in the elongation of theyarn.

The textile fibre from which the sheath is formed can be any naturalfibre in staple or continuous filament form, such as cotton, or wool, orany synthetic fibre, such as, for example, nylon, rayon,polyacrylonitrile, or polyethylene terephthalate. The elastic filamentconstituting the core of the yarn is preferably formed from a long chainsynthetic polymer composed of at least percent of a segmentedpolyurethane of the kind known as Spandex.

The present invention enables an elastic filament to be introduced to adrafting zone under predetermined and positively controlled conditionsof elongation and modulus so as to produce a uniformand consistent yarnhaving the desired elastic properties. The controlled conditions can bevaried from zero up to the ultImate stretch limit of the elasticfilament.

Existing spinning machinery can readily be modified to adapt it toproduce yarns in accordance with the invention and conveniently theapparatus can be constructed in the form of an attachment to an existingmachine.

I claim:

1. A method of spinning an elastic high-bulk yarn comprising the stepsof providing an elastic filament wound under tension on a package,causing said package to rotate at a predetermined speed, unwinding saidfilament from said package at a predetermined linear speed, feeding saidfilament onto a positively driven pulley to cause said filament totravel in an undulating path and to restrain it against slippage,advancing the filament from the pulley through a pretensioning zone to afinal drafting zone, advancing said filament under uniform tensionthrough the final drafting zone, drafting one or more rovings ofinelastic filaments, gathering said elastic filament and said draftedrovings in the final drafting zone and thereafter twisting said rovingsabout said filament to form a sheath thereto.

2. A method according to claim 1, wherein the elastic filament is formedfrom a segmented elastomer.

3. Apparatus for spinning an elastic high-bulk yarn comprising a packagewound with elastic filament and adapted to be rotatably driven to unwindsaid filament therefrom at a predetermined linear speed, 'a rotatablydriven V-pulley adapted to receive said filament and to advance itwithout slippage through a pretensioning zone to the nip of a first pairof draft rollers, at least one package having Wound thereon rovings ofinelastic filaments, a drafting system for said inelastic rovingsunwound from said package or packages, a second pair of draft rolls forreceiving the elastic filament from said first pair of draft rolls, saidelastic filament and said rovings being passed together between saidsecond pair of draft rolls, a guide for said drafted elastic filamentand rovings and means for twisting said rovings around sa'd elasticfilament, the speeds of the pulley and the first and second pairs ofdraft rolls being correlated with each other in such a manner that theelastic filament is pretensioned between the pulley and the first pairof rolls and passed from said first pair of rolls to said second pair ofrolls under a uniform and constant tension.

4. Apparatus according to claim 3, wherein said pulley comprises a pairof dished plates each formed with a plurality of equidistantly spacedoutwardly inclined radial tongues and a central aperture, said platesbeing so assembled that the tongues on one plate interengage the gapsbetween the tongues on the other plate, whereby the periphery of thebase of the pulley V-groove will have an undulating elasticfilament-contacting surface to restrain said filament against slippage;

5. Apparatus according to claim 4, wherein a boss is located within thecentral apertures in said plates, said plates being fixedly secured tosaid boss.

6. Apparatus according to claim 5, wherein a hoop is located on andsecured to the outer edge of each of said plates to provide a smoothfinish thereto.

References Cited UNITED STATES PATENTS 2,074,199 3/1937 Arnold 57-9O X2,210,884 8/1940 Chittenden et a1 57l2 X 3,243,950 4/1966 Hermes 57163FRANK J. COHEN, Primary Examiner.

W. S. BURDEN, Assistant Examiner.

3. APPARATUS FOR SPINNING AN ELASTIC HIGH-BULK YARN COMPRISING A PACKAGEWOUND WITH ELASTIC FILMENT AND ADAPTED TO BE ROTATABLY DRIVEN TO UNWINDSAID FILAMENT THEREFROM AT A PREDETERMINED LINEAR SPEED, A ROTATABLYDRIVEN V-PULLEY ADAPTED TO RECEIVE SAID FILAMENT AND TO ADVANCE ITWITHOUT SLIPPAGE THROUGH A PRETENSIONING ZONE TO THE NIP OF A FIRST PAIROF DRAFT ROLLERS, AT LEAST ONE PACKAGE HAVING WOUND THEREON ROVINGS OFINELASTIC FILAMENTS, A DRAFTING SYSTEM FOR SAID INELASTIC ROVINGSUNWOUND FROM SAID PACKAGE OR PACKAGES, A SECOND PAIR OF DRAFT ROLLS FORRECEIVING THE ELASTIC FILAMENT FROM SAID FIRST PAIR OF DRAFT ROLLS, SAIDELASTIC FILAMENT AND SAID ROVINGS BEING PASSED TOGETHER BETWEEN SAIDSECOND PAIR OF DRAFT ROLLS, A GUIDE FOR SAID DRAFTED ELASTIC FILAMENTAND ROVINGS AND MEANS FOR TWISTING SAID ROVINGS AROUND SAID ELASTICFILAMENT, THE SPEEDS OF THE PULLEY AND THE FIRST AND SECOND PAIRS OFDRAFT ROLLS BEING CORRELATED WITH EACH OTHER IN SUCH A MANNER THAT THEELASTIC FILAMENT IS PRETENSIONED BETWEEN THE PULLEY AND THE FIRST PAIROF ROLLS AND PASSED FROM SAID FIRST PAIR OF ROLLS TO SAID SECOND PAIR OFROLLS UNDER A UNIFORM AND CONSTANT TENSION.